Suppression of starch synthesis in rice stems splays tiller angle due to gravitropic insensitivity but does not affect yield

2015 ◽  
Vol 42 (1) ◽  
pp. 31 ◽  
Author(s):  
Masaki Okamura ◽  
Tatsuro Hirose ◽  
Yoichi Hashida ◽  
Ryu Ohsugi ◽  
Naohiro Aoki
Keyword(s):  
Double Mutant ◽  
Oryza Sativa L ◽  
Starch Content ◽  
Large Subunit ◽  
Starch Synthesis ◽  
Starch Accumulation ◽  
Gravitropic Response ◽  
Rice Mutant ◽  
Matter Production ◽  
Tiller Angle

In rice (Oryza sativa L.), tiller angle – defined as the angle between the main culm and its side tillers – is one of the important factors involved in light use efficiency. To clarify the relationship between tiller angle, gravitropism and stem-starch accumulation, we investigated the shoot gravitropic response of a low stem-starch rice mutant which lacks a large subunit of ADP-glucose pyrophosphorylase (AGP), called OsAGPL1 and exhibits relatively spread tiller angle. The insensitive gravitropic response exhibited by the mutant led us to the conclusion that insensitivity of gravitropism caused by stem-starch reduction splayed the tiller angle. Furthermore, since another AGP gene called OsAGPL3 was expressed at considerable levels in graviresponding sites, we generated a double mutant lacking both OsAGPL1 and OsAGPL3. The double mutant exhibited still lower stem-starch content, less sensitive gravitropic response and greater tiller angle spread than the single mutants. This indicated that the expansion of the tiller angle caused by the reduction in starch level was intense according to the extent of the reduction. We found there were no significant differences between the double mutant and wild-type plants in terms of dry matter production. These results provided new insight into the importance of stem-starch accumulation and ideal plant architecture.

A rice mutant lacking a large subunit of ADP-glucose pyrophosphorylase has drastically reduced starch content in the culm but normal plant morphology and yield

2012 ◽  
Vol 39 (12) ◽  
pp. 1068 ◽  
Author(s):  
Frederick R. Cook ◽  
Brendan Fahy ◽  
Kay Trafford
Keyword(s):  
No Reduction ◽  
Oryza Sativa L ◽  
Starch Content ◽  
Large Subunit ◽  
Plant Morphology ◽  
Gene Encoding ◽  
Rice Mutant ◽  
Carbohydrate Storage ◽  
Adp Glucose Pyrophosphorylase ◽  
Storage Pools

A mutant of rice (Oryza sativa L.) was identified with a Tos17 insertion in Os05g50380, a gene encoding a plastidial large subunit (LSU) of ADP-glucose pyrophosphorylase (AGPase) that was previously called OsAPL3 or OsAGPL1. The insertion prevents the production of a normal transcript. Characterisation of the mutant showed that this LSU is required for 97% of the starch synthesised in the flowering stem (culm), approximately half of the AGPase activity in developing embryos and that it contributes to AGPase activity in the endosperm. Despite the near absence of starch in the culms and reduced starch content in the embryos, the mutant rice plants grow and develop normally, and show no reduction in productivity. The starch content of leaves is increased in the mutant, revealing plasticity in the distribution of photosynthates among different temporary carbohydrate storage pools within the plant.

scholarly journals Increasing Starch Accumulation via Genetic Modification of the ADP-glucose Pyrophosphorylase

2009 ◽  
Author(s):  
Arthur Schaffer ◽  
Jack Preiss ◽  
Marina Petreikov ◽  
Ilan Levin
Keyword(s):  
Starch Content ◽  
Large Subunit ◽  
Tomato Fruit ◽  
Sugar Content ◽  
Soluble Sugar ◽  
Starch Synthesis ◽  
Regulatory Subunit ◽  
Starch Accumulation ◽  
Research Project ◽  
Immature Fruit

The overall objective of the research project was to utilize biochemical insights together with both classical and molecular genetic strategies to improve tomato starch accumulation. The proposal was based on the observation that the transient starch accumulation in the immature fruit serves as a reservoir for carbohydrate and soluble sugar content in the mature fruit, thereby impacting on fruit quality. The general objectives were to optimize AGPase function and activity in developing fruit in order to increase its transient starch levels. The specific research objectives were to: a) perform directed molecular evolution of the limiting enzyme of starch synthesis, AGPase, focussing on the interaction of its regulatory and catalytic subunits; b) determine the mode of action of the recently identified allelic variant for the regulatory subunit in tomato fruit that leads to increased AGPase activity and hence starch content. During the course of the research project major advances were made in understanding the interaction of the small and large subunits of AGPase, in particular the regulatory roles of the different large subunits, in determining starch synthesis. The research was performed using various experimental systems, including bacteria and Arabidopsis, potato and tomato, allowing for broad and meaningful conclusions to be drawn. A novel discovery was that one of the large subunits of tomato AGPase is functional as a monomer. A dozen publications describing the research were published in leading biochemical and horticultural journals. The research results clearly indicated that increasing AGPase activity temporally in the developing fruit increase the starch reservoir and, subsequently, the fruit sugar content. This was shown by a comparison of the carbohydrate balance in near-isogenic tomato lines differing in a gene encoding for the fruit-specific large subunit (LS1). The research also revealed that the increase in AGPase activity is due to a temporal extension of LS1 gene expression in the developing fruit which in turn stabilizes the limiting heterotetrameric enzyme, leading to sustained starch synthesis. This genetic variation can successfully be utilized in the breeding of high quality tomatoes.

scholarly journals Silencing GhAGPL1 Reduces the Quality and Quantity of Corms and Cormels in Gladiolus

2017 ◽  
Vol 142 (2) ◽  
pp. 119-125 ◽  
Author(s):  
Shanshan Seng ◽  
Jian Wu ◽  
Jiahui Liang ◽  
Fengqin Zhang ◽  
Qiuyan Yang ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Abscisic Acid ◽  
Starch Content ◽  
Large Subunit ◽  
Starch Synthesis ◽  
Transcript Level ◽  
Starch Accumulation ◽  
Sucrose Content ◽  
Gladiolus Hybridus ◽  
Rate Limiting

Starch accumulation is important during com development. ADP-glucose pyrophosphorylase (AGPase) is the rate-limiting enzyme in starch synthesis. AGPL is the large subunit of AGPase. Here, we isolated and characterized the large subunit of AGPase gene GhAGPL1 in gladiolus (Gladiolus hybridus). GhAGPL1 was highly expressed in sink organs (cormels and corms). The expression of GhAGPL1 was induced by glucose, sucrose, and mannitol, and it was repressed by abscisic acid (ABA). Overexpression of GhAGPL1 in the arabidopsis (Arabidopsis thaliana) apl1 mutant resulted in complementation of AGPase activity and thus starch synthesis. Silencing GhAGPL1 in gladiolus decreased the transcript level of GhAGPL1 and GhSus, and resulted in the reduction of AGPase activity and starch content in gladiolus corm and cormel. Meanwhile, sucrose content was higher in GhAGPL1-silenced corm. Surprisingly, silencing GhAGPL1 in gladiolus produced smaller corms and fewer number of cormels. Overall, GhAGPL1 contributed to the quality and quantity of gladiolus corms and cormels.

Starch reduction in rice stems due to a lack of OsAGPL1 or OsAPL3 decreases grain yield under low irradiance during ripening and modifies plant architecture

2013 ◽  
Vol 40 (11) ◽  
pp. 1137 ◽  
Author(s):  
Masaki Okamura ◽  
Tatsuro Hirose ◽  
Yoichi Hashida ◽  
Tohru Yamagishi ◽  
Ryu Ohsugi ◽  
...  
Keyword(s):  
Grain Yield ◽  
Plant Architecture ◽  
Oryza Sativa L ◽  
Large Subunit ◽  
Dry Weight ◽  
Leaf Sheath ◽  
Starch Accumulation ◽  
Wild Type ◽  
Gene Encoding ◽  
Rice Mutant

Starch accumulated in rice (Oryza sativa L.) stems before heading as nonstructural carbohydrates (NSCs) is reported to be important for improving and stabilising grain yield. To evaluate the importance of stem starch, we investigated a retrotransposon (Tos17) insertion rice mutant lacking a gene encoding a large subunit of ADP-glucose pyrophosphorylase (AGP) called OsAGPL1 or OsAPL3. The AGP activity and starch contents of the mutant were drastically reduced in the stem (i.e. leaf sheath and culm) but not in the leaf blade or endosperm. This starch reduction in the leaf sheaths of the mutant was complemented by the introduction of wild-type OsAGPL1. These results strongly suggest that OsAGPL1 plays a principal role in stem starch accumulation. Field experimentations spanning 2 years revealed that the mutant plants were shorter than the wild-type plants. Moreover, the tiller number and angle were larger in the mutant plants than the wild-type plants, but the dry weight at heading stage was not different. The grain yield was slightly lower in control plots without shading treatment. However, this difference increased substantially with shading. Therefore, stem starch is indispensable for normal ripening under low irradiance conditions and probably contributes to the maintenance of appropriate plant architecture.

scholarly journals Starch synthesis and gelatinization properties of potato tubers

2022 ◽  
Vol 52 (4) ◽  
Author(s):  
Wang Su ◽  
Guangji Ye ◽  
Yun Zhou ◽  
Jian Wang
Keyword(s):  
Gene Expression ◽  
Enzyme Activity ◽  
Starch Granule ◽  
Starch Content ◽  
Starch Synthesis ◽  
Starch Accumulation ◽  
Enzyme Gene ◽  
Middle Stage ◽  
Pasting Temperature ◽  
Starch Synthesis Enzyme

ABSTRACT: Biosynthesis is the only source of potato starch which is an important raw material for food processing, modified starch and biomass energy. However, it is not clear about the evolution of starch synthesis with tuber development in potato. The present study evaluated the differences of starch synthesis and gelatinization properties of potato tubers with different starch content. Relative to cultivars of medium and low starch content, cultivars of high starch content showed significantly higher SBEII gene expression, AGPase and SSS enzyme activity, and total starch content after middle stage of starch accumulation, and had smaller average starch granule size during whole process of tuber development, and had higher pasting temperature before late stages of tuber growth, and had lower pasting temperature after middle stage of starch accumulation. Path analysis showed that, after middle stage of starch accumulation, effects on starch gelatinization of cultivars with high, medium and low starch content represented starch synthesis enzyme activity > starch accumulation > starch granule distribution > starch synthesis enzyme gene expression, starch synthesis enzyme gene expression > starch synthesis enzyme activity > starch accumulation > starch granule distribution, starch synthesis enzyme gene expression > starch granule distribution > starch synthesis enzyme activity > starch accumulation, respectively. In the study, phases existed in the starch biosynthesis of potato tuber, and the starch quality and its formation process were different among varieties with different starch content. The findings might contribute to starch application and potato industries.

scholarly journals CO2-Responsive CCT Protein interacts with 14-3-3 proteins and controls the expression of starch synthesis-related genes

2021 ◽  
Author(s):  
Hiroshi Fukayama ◽  
Naoki Shibatani ◽  
Hirofumi Miyagawa ◽  
Aiko Koudou ◽  
Yasuo Yamauchi ◽  
...  
Keyword(s):  
Oryza Sativa L ◽  
Large Subunit ◽  
Starch Synthesis ◽  
Gel Filtration ◽  
Parenchyma Cell ◽  
Mesophyll Cell ◽  
Leaf Sheath ◽  
Bimolecular Fluorescence Complementation ◽  
Promoter Regions

CO2 responsive CCT protein (CRCT) is a positive regulator of starch synthesis related genes such as ADP-glucose pyrophosphorylase large subunit 1 and starch branching enzyme I particularly in the leaf sheath of rice (Oryza sativa L.). The promoter GUS analysis revealed that CRCT expressed exclusively in the vascular bundle, whereas starch synthesis related genes were expressed in different sites such as mesophyll cell and starch storage parenchyma cell. However, the chromatin immunoprecipitation (ChIP) using a FLAG-CRCT overexpression line and subsequent qPCR analyses showed that the 5’-flanking regions of these starch synthesis-related genes tended to be enriched by ChIP, suggesting that CRCT can bind to the promoter regions of these genes. The monomer of CRCT is 34.2 kDa, however CRCT was detected at 270 kDa via gel filtration chromatography, suggesting that CRCT forms a complex in vivo. Immunoprecipitation and subsequent MS analysis pulled down several 14-3-3-like proteins. A yeast two-hybrid analysis and bimolecular fluorescence complementation assays confirmed the interaction between CRCT and 14-3-3-like proteins. Although there is an inconsistency in the place of expression, this study provide important findings regarding the molecular function of CRCT to control the expression of key starch synthesis-related genes.

scholarly journals Expression of Maize MADS Transcription Factor ZmES22 Negatively Modulates Starch Accumulation in Rice Endosperm

2019 ◽  
Vol 20 (3) ◽  
pp. 483 ◽  
Author(s):  
Kangyong Zha ◽  
Haoxun Xie ◽  
Min Ge ◽  
Zimeng Wang ◽  
Yu Wang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Mrna Expression ◽  
Starch Content ◽  
Soluble Sugar ◽  
Starch Synthesis ◽  
Synthesis Process ◽  
Starch Accumulation ◽  
Rice Grain ◽  
Altered Expression ◽  
Rice Endosperm

As major component in cereals grains, starch has been one of the most important carbohydrate consumed by a majority of world’s population. However, the molecular mechanism for regulation of biosynthesis of starch remains elusive. In the present study, ZmES22, encoding a MADS-type transcription factor, was modestly characterized from maize inbred line B73. ZmES22 exhibited high expression level in endosperm at 10 days after pollination (DAP) and peaked in endosperm at 20 DAP, indicating that ZmES22 was preferentially expressed in maize endosperm during active starch synthesis. Transient expression of ZmES22 in tobacco leaf revealed that ZmES22 protein located in nucleus. No transactivation activity could be detected for ZmES22 protein via yeast one-hybrid assay. Transformation of overexpressing plasmid 35S::ZmES22 into rice remarkedly reduced 1000-grain weight as well as the total starch content, while the soluble sugar was significantly higher in transgenic rice lines. Moreover, overexpressing ZmES22 reduced fractions of long branched starch. Scanning electron microscopy images of transverse sections of rice grains revealed that altered expression of ZmES22 also changed the morphology of starch granule from densely packed, polyhedral starch granules into loosely packed, spherical granules with larger spaces. Furthermore, RNA-seq results indicated that overexpressing ZmES22 could significantly influence mRNA expression levels of numerous key regulatory genes in starch synthesis pathway. Y1H assay illustrated that ZmES22 protein could bind to the promoter region of OsGIF1 and downregulate its mRNA expression during rice grain filling stages. These findings suggest that ZmES22 was a novel regulator during starch synthesis process in rice endosperm.

scholarly journals Maize endosperm-specific transcription factors O2 and PBF network the regulation of protein and starch synthesis

2016 ◽  
Vol 113 (39) ◽  
pp. 10842-10847 ◽  
Author(s):  
Zhiyong Zhang ◽  
Xixi Zheng ◽  
Jun Yang ◽  
Joachim Messing ◽  
Yongrui Wu
Keyword(s):  
Transcription Factors ◽  
Double Mutant ◽  
Starch Content ◽  
Starch Synthesis ◽  
Starch Synthase ◽  
Maize Endosperm ◽  
Protein Levels ◽  
Pyruvate Orthophosphate Dikinase ◽  
Branching Enzymes ◽  
Critical Components

The maize endosperm-specific transcription factors opaque2 (O2) and prolamine-box binding factor (PBF) regulate storage protein zein genes. We show that they also control starch synthesis. The starch content in the PbfRNAi and o2 mutants was reduced by ∼5% and 11%, respectively, compared with normal genotypes. In the double-mutant PbfRNAi;o2, starch was decreased by 25%. Transcriptome analysis reveals that >1,000 genes were affected in each of the two mutants and in the double mutant; these genes were mainly enriched in sugar and protein metabolism. Pyruvate orthophosphate dikinase 1 and 2 (PPDKs) and starch synthase III (SSIII) are critical components in the starch biosynthetic enzyme complex. The expression of PPDK1, PPDK2, and SSIII and their protein levels are further reduced in the double mutants as compared with the single mutants. When the promoters of these genes were analyzed, we found a prolamine box and an O2 box that can be additively transactivated by PBF and O2. Starch synthase IIa (SSIIa, encoding another starch synthase for amylopectin) and starch branching enzyme 1 (SBEI, encoding one of the two main starch branching enzymes) are not directly regulated by PBF and O2, but their protein levels are significantly decreased in the o2 mutant and are further decreased in the double mutant, indicating that o2 and PbfRNAi may affect the levels of some other transcription factor(s) or mRNA regulatory factor(s) that in turn would affect the transcript and protein levels of SSIIa and SBEI. These findings show that three important traits—nutritional quality, calories, and yield—are linked through the same transcription factors.

The NAC transcription factor NAC019-A1 is a negative regulator of starch synthesis in wheat developing endosperm

2020 ◽  
Vol 71 (19) ◽  
pp. 5794-5807
Author(s):  
Yunchuan Liu ◽  
Jian Hou ◽  
Xiaolu Wang ◽  
Tian Li ◽  
Uzma Majeed ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Oryza Sativa L ◽  
Starch Content ◽  
Wheat Yield ◽  
Starch Synthesis ◽  
Kernel Weight ◽  
Nac Transcription Factor ◽  
Negative Regulator ◽  
Starch Granules ◽  
Wheat Endosperm

Abstract Starch is a major component of wheat (Triticum aestivum L.) endosperm and is an important part of the human diet. The functions of many starch synthesis genes have been elucidated. However, little is known about their regulatory mechanisms in wheat. Here, we identified a novel NAC transcription factor, TaNAC019-A1 (TraesCS3A02G077900), that negatively regulates starch synthesis in wheat and rice (Oryza sativa L.) endosperms. TaNAC019-A1 was highly expressed in the endosperm of developing grains and encoded a nucleus-localized transcriptional repressor. Overexpression of TaNAC019-A1 in rice and wheat led to significantly reduced starch content, kernel weight, and kernel width. The TaNAC019-A1-overexpression wheat lines had smaller A-type starch granules and fewer B-type starch granules than wild-type. Moreover, TaNAC019-A1 could directly bind to the ‘ACGCAG’ motif in the promoter regions of ADP-glucose pyrophosphorylase small subunit 1 (TaAGPS1-A1, TraesCS7A02G287400) and TaAGPS1-B1 (TraesCS7B02G183300) and repress their expression, thereby inhibiting starch synthesis in wheat endosperm. One haplotype of TaNAC019-B1 (TaNAC019-B1-Hap2, TraesCS3B02G092800) was positively associated with thousand-kernel weight and underwent positive selection during the Chinese wheat breeding process. Our data demonstrate that TaNAC019-A1 is a negative regulator of starch synthesis in wheat endosperm and provide novel insight into wheat yield improvement.

A mutant of rice lacking the leaf large subunit of ADP-glucose pyrophosphorylase has drastically reduced leaf starch content but grows normally

2007 ◽  
Vol 34 (6) ◽  
pp. 480 ◽  
Author(s):  
Sandrine Rösti ◽  
Brendan Fahy ◽  
Kay Denyer
Keyword(s):  
Environmental Conditions ◽  
No Reduction ◽  
Starch Content ◽  
Large Subunit ◽  
Starch Synthesis ◽  
Small Subunit ◽  
Wild Type ◽  
Gene Encoding ◽  
Subunit Protein ◽  
Adp Glucose Pyrophosphorylase

A mutant of rice was identified with a Tos17 insertion in OsAPL1, a gene encoding a large subunit (LSU) of ADP-glucose pyrophosphorylase (AGPase). The insertion prevents production of a normal transcript from OsAPL1. Characterisation of the mutant (apl1) showed that the LSU encoded by OsAPL1 is required for AGPase activity in rice leaf blades. In mutant leaf blades, the AGPase small subunit protein is not detectable and the AGPase activity and starch content are reduced to <1 and <5% of that in wild type blades, respectively. The mutation also leads to a reduction in starch content in the leaf sheaths but does not significantly affect AGPase activity or starch synthesis in other parts of the plant. The sucrose, glucose and fructose contents of the leaves are not affected by the mutation. Despite the near absence of starch in the leaf blades, apl1 mutant rice plants grow and develop normally under controlled environmental conditions and show no reduction in productivity.

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